The present invention relates to an electric compressor including an electric motor, and more particularly, to a sealed terminal connected to a lead wire of an electric motor.
An electric compressor includes an electric motor, which is accommodated in a sealed compressor housing. A sealed terminal is arranged on the compressor housing to electrically connect a lead wire of the electric motor and an inverter, which is arranged outside the compressor housing to drive the electric motor. The sealed terminal includes a terminal pin, which is formed from a conductive material, and a metal terminal holder, which holds the terminal pin. An insulative material, such as a ceramic or glass, is arranged between the terminal pin and the terminal holder.
Japanese Laid-Open Patent Publication No. 2010-1882 discloses an electric compressor that accommodates an electric motor and a compression mechanism, which is driven by the electric motor, in a motor housing. A platform is arranged on an outer surface of the motor housing. An inverter is arranged on the platform to convert DC power, which is supplied from outside the electric compressor, into three-phase AC power and control the rotation speed of the electric motor. A through hole extends through the motor housing in front of the inverter. A sealed terminal is arranged in the through hole. The sealed terminal includes a terminal body and a conductive member, which is formed from a metal and extends through a hole arranged in the terminal body. Insulative adhesive is applied to the conductive member at a portion located inside the hole of the terminal body. This fixes the terminal body and the conductive body integrally with each other.
At the lower side of the terminal body, a side wall of the terminal body has an edge that projects into the motor housing and forms a flange, which extends outward. The terminal body includes a portion located in the through hole of the motor housing. A groove extends throughout the entire circumference of this portion. An O-ring, which serves as a sealing means, is arranged in the groove. The O-ring seals the inner side of the motor housing from an inverter accommodation compartment, which is the outer side of the motor housing. This seals the motor housing. A cluster block, which electrically connects the sealed terminal to the electric motor, is arranged under the sealed terminal. The cluster block is spaced apart from the sealed terminal. The lower end of the conductive member extends into the cluster block through a hole arranged in a top surface of the cluster block and is electrically connected by a connection terminal and lead wire to the electric motor.
In a structure in which the cluster block is spaced apart from the sealed terminal like in the above publication, the cluster block and sealed terminal can be freely laid out. Thus, there is no need for a special fastening means. This is advantageous since the structure in the motor housing is simpler than a structure that arranges the cluster block in contact with the sealed terminal.
However, a refrigerant freely circulates between the sealed terminal and the cluster block. This causes various problems. For example, fine particles produced by wear of the interior of the electric compressor and pipes, which form an external refrigerant circuit, are suspended in the refrigerant circulating through the electric compressor. The particles may include relatively elongated particles that are caught and collected on the terminal body of the sealed terminal, the exposed connection terminal, or near the through hole for the sealed terminal in the motor housing. Collected elongated particles may cause contact and short-circuiting between the connection terminal and one or both of the terminal body and motor housing. As a result, electricity may leak to the motor housing of the electric compressor.
For example, in a scroll type electric compressor, a large amount of abrasive particles produced when wear occurs in a metal plating of a scroll and in metal members inside the electric compressor and of an outer refrigerant circuit may be suspended in the circulating refrigerant. When, for example, a sealed terminal includes a terminal body fixed by a ceramic insulator to a connection terminal, the ceramic insulator is exposed to the circulating refrigerant. As a result, a large amount of the abrasive particles suspended in the refrigerant are apt to entering and collecting in fine pores of the ceramic insulator. The abrasive particles deposited on the connection terminal may cause short-circuiting between the connection terminal and the terminal body. As a result, electricity may leak to the motor housing of the electric compressor.